U.S. patent application number 10/928591 was filed with the patent office on 2005-03-17 for ratio controller with dynamic ratio formation.
Invention is credited to Moses, Johann.
Application Number | 20050058961 10/928591 |
Document ID | / |
Family ID | 34089273 |
Filed Date | 2005-03-17 |
United States Patent
Application |
20050058961 |
Kind Code |
A1 |
Moses, Johann |
March 17, 2005 |
Ratio controller with dynamic ratio formation
Abstract
For adjustment of a desired burner gas-air ratio over the
broadest possible load range without additional pressure tapping of
the burner, combustion chamber, or air lines, a ratio controller is
provided that permits adjustment of the gas flow as a function of
counterpressure. For adjustment, the ratio controller has at least
one position-variable measurement site, or at least two measurement
sites, connected directly or indirectly via a pilot valve, to an
actuating diaphragm via a valve block or throttle valve block.
Depending on whether the control pressure is picked up more from
one or more from the other measurement site, the gas flow and
therefore the gas-air ratio can be adjusted to be larger or
smaller.
Inventors: |
Moses, Johann; (Schorndorf,
DE) |
Correspondence
Address: |
REED SMITH, LLP
ATTN: PATENT RECORDS DEPARTMENT
599 LEXINGTON AVENUE, 29TH FLOOR
NEW YORK
NY
10022-7650
US
|
Family ID: |
34089273 |
Appl. No.: |
10/928591 |
Filed: |
August 27, 2004 |
Current U.S.
Class: |
431/90 |
Current CPC
Class: |
F23D 14/60 20130101;
F23N 2235/24 20200101; Y10T 137/7764 20150401; F23N 1/027 20130101;
Y10T 137/7762 20150401; F23N 2235/20 20200101 |
Class at
Publication: |
431/090 |
International
Class: |
F23N 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2003 |
DE |
103 40 045.1 |
Claims
What is claimed is:
1. A ratio controller for fuel gas metering of a gas burner
comprising: a housing, in which at least one valve seat and at
least one valve closure element adjustably associated with it are
arranged, which divides the interior of the valve housing into an
inflow chamber and an outflow chamber, an actuating diaphragm, to
which the valve closure element is connected, in order to adjust
this according to a pressure difference, and a pulse channel to
influence the actuating diaphragm, in which pressure tapping is
effected via the pulse channel at an adjustable measurement site,
simultaneously at at least two different measurement sites of the
outflow chamber, at a connected gas line with different flow
conditions, or combinations thereof.
2. The ratio controller according to claim 1, wherein an adjustment
device for adjusting the position of the pressure tap is arranged
on the ratio controller.
3. The ratio controller according to claim 2, wherein the different
positions of the adjustment device differ by a different flow
direction of the pressure tap.
4. The ratio controller according to claim 2, wherein the different
positions of the adjustment device differ by the different flow
cross sections at the pressure tap.
5. The ratio controller according to claim 1, wherein the pulse
channel is connected to a pilot control valve.
6. The ratio controller according to claim 1, wherein branches
belong to the pulse channel and lead from different measurement
sites of the outflow chamber or gas line to a pneumatic ratio
adjustment valve that is connected to a pilot control valve.
7. The ratio controller according to claim 6, wherein an adjustable
throttle valve is arranged in at least one of the branches.
8. The ratio controller according to claim 6, wherein a three/two
distribution valve is arranged between branches.
9. The ratio controller according to claim 7, wherein the throttle
valve is continuously adjustable.
10. The ratio controller according to claim 8, wherein the
three/two distribution valve is continuously adjustable.
11. The ratio controller according to claim 9, wherein the throttle
valve is adjustable by means of a servodrive by means of a control
device.
12. The ratio controller according to claim 1, wherein the pilot
valve has a control diaphragm, acted upon on one side by the
pressure of the pulse line, which controls a pressure channel that
leads from the inflow chamber to the diaphragm valve.
13. The ratio controller according to claim 12, wherein the other
side of the control diaphragm is acted upon by the ambient air
pressure.
14. The ratio controller according to claim 12, wherein the other
side of the control diaphragm is acted upon by the pressure
prevailing in front of a gas/air mixture formation device.
15. The ratio controller according to claim 1, wherein a connection
channel is provided between the outflow chamber and the actuating
diaphragm.
16. The ratio controller according to claim 10, wherein the
three/two distribution valve is adjustable by means of a servodrive
by means of a control device.
17. A ratio controller for fuel gas metering of a gas burner
comprising: a housing having at least one valve seat and at least
one valve closure element adjustably associated with it arranged so
that the interior of the valve housing is divided into an inflow
chamber and an outflow chamber, an actuating diaphragm is connected
to the valve closure element to adjust the actuating diaphragm
according to a pressure difference, and a pulse channel to
influence the actuating diaphragm, in which pressure tapping is
effected by the pulse channel at an adjustable measurement site,
simultaneously at at least two different measurement sites of the
outflow chamber, at least two different flow conditions of a
connected gas line, or combinations thereof.
18. The ratio controller according to claim 17, wherein an
adjustment device for adjusting the position of the pressure tap is
arranged on the ratio controller.
19. The ratio controller according to claim 18, wherein the
different positions of the adjustment device differ by a different
flow direction of the pressure tap.
20. The ratio controller according to claim 18, wherein the
different positions of the adjustment device differ by the
different flow cross sections at the pressure tap.
21. The ratio controller according to claim 17, wherein the pulse
channel is connected to a pilot control valve.
22. The ratio controller according to claim 17 wherein branches
belong to the pulse channel and lead from different measurement
sites of the outflow chamber or gas line to a pneumatic ratio
adjustment valve that is connected to a pilot control valve.
23. The ratio controller according to claim 22, wherein an
adjustable throttle valve is arranged in at least one of the
branches.
24. The ratio controller according to claim 22, wherein a three/two
distribution valve is arranged between branches.
25. The ratio controller according to claim 23, wherein the
throttle valve is continuously adjustable.
26. The ratio controller according to claim 24, wherein the
three/two distribution valve is continuously adjustable.
27. The ratio controller according to claim 25, wherein the
throttle valve is adjustable by means of a servodrive by means of a
control device.
28. The ratio controller according to claim 17, wherein the pilot
valve has a control diaphragm, acted upon on one side by the
pressure of the pulse line, which controls a pressure channel that
leads from the inflow chamber to the diaphragm valve.
29. The ratio controller according to claim 28, wherein the other
side of the control diaphragm is acted upon by the ambient air
pressure.
30. The ratio controller according to claim 28, wherein the other
side of the control diaphragm is acted upon by the pressure
prevailing in front of a gas/air mixture formation device.
31. The ratio controller according to claim 17, wherein a
connection channel is provided between the outflow chamber and the
actuating diaphragm.
32. The ratio controller according to claim 26, wherein the
three/two distribution valve is adjustable by means of a servodrive
by means of a control device.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to German Application No.
103 40 045.1, filed Aug. 28, 2003, all of which are incorporated
herein by reference.
TECHNICAL FIELD OF THE INVENTION
[0002] The present invention is directed generally to a ratio
controller for fuel gas metering in gas burners.
BACKGROUND OF THE INVENTION
[0003] The invention concerns a ratio controller, especially for
fuel gas metering in gas burners, for example, forced-air
burners.
[0004] In gas burners, a stipulated gas-air ratio must be set at
the burners in order to ensure correct operation. The gas-air ratio
must then be set independently of the load state. For burners that
are in particular to be operated not only at nominal load, but also
at partial load, this requires re-adjustment of the gas feed
corresponding to air feed. The aim is to permit this with simple,
robust and versatile devices.
[0005] In the design of gas heating installations, gas boilers and
gas burners, system suppliers generally resort to vendor parts that
can be incorporated into the overall system that are as much as
possible problem-free. An effort is made, in particular, to assure
that the assemblies, for example, appropriate ratio controllers,
require no special control signals from other assemblies, in order
to set the desired gas-air ratio correctly. Additional pressure
taps or pressure lines, for example, from the burner to the ratio
controller, represent undesirable limitations from the standpoint
of the system supplier.
[0006] A ratio controller that regulates the gas feed to a burner
is known from DE 197 40 666 C1. A ratio controller, to which a
first pressure tap in the gas line and a second pressure tap in the
combustion chamber are connected, is used for the desired
adjustment of a stipulated gas-air ratio. Both pressure taps are
provided with a throttle valve. Gas flows into the combustion
chamber via the connection path between the two taps. A control
pressure for the ratio controller is tapped between the throttle
valve valves.
[0007] An additional pressure tap in the combustion chamber is
often not present, so that use of this ratio controller is
restricted.
[0008] Another ratio controller is known from EP 06 44 377 B1,
which is formed by a pilot-controlled control valve provided with
an actuating diaphragm. A pressure tap in the gas line leading to
the burner, as well as two additional pressure taps in the air line
leading from a blower to the burner, serve for pilot control. The
two pressure taps in the air line record the pressure difference
across a throttle valve location.
[0009] In this arrangement, an undesired hampering of air flow
develops through the throttle valve location behind the forced-air
burner. The pressure drop caused by the throttle valve must be
overcome by the blower. This should be done in particular with
respect to possible adjustments to different burner operating
conditions, like loads, etc., as well as with respect to varying
gas composition or the like.
[0010] With this as the point of departure, the task of the
invention was to devise a simple and robust ratio controller
without external pressure taps.
SUMMARY OF THE INVENTION
[0011] The present invention provides a ratio controller without
external pressure taps. The ratio controller according to the
invention has a main valve with an actuating diaphragm, in which a
pulse channel serves to control the actuating diaphragm. This
permits pressure tapping of the outflow chamber of the ratio
controller selective or simultaneous of at least two different
measurement sites. By choosing the measurement site, the gas
pressure occurring at the output of the ratio controller as a
function of the gas velocity can be regulated to correspond to a
stipulated gas-air ratio. It is also possible to maintain this
gas-air ratio over different load conditions from an extremely low
load to full load. No external pressure taps are required for
this.
[0012] Formation of the correct pressure ratio at the gas nozzle is
effected as a function of the pressure difference at the air feed
(air nozzle). If the air nozzle and gas nozzle, for example, are
seated at the blower intake connection, both the air pressure and
the gas pressure in front of the gas nozzle diminish uniformly with
increasing blower speed and therefore increasing air throughput.
Readjustment of the ratio controller is therefore effected by means
of the gas pressure in front of the gas nozzle. This occurs
pneumatically by means of a special throttle valve arrangement. The
pressure controller is set so that it roughly adjusts the static
pressure (atmospheric pressure) at the gas nozzle. Opening of the
controller then occurs pneumatically from the pressure applied
during an air and gas reduction.
[0013] The pressure taken off on the outflow side of the valve
directly in the outflow chamber, or also at the gas nozzle, and a
pressure tapped at another location together form in an adjustable
ratio a control pressure to control the pilot valve for the ratio
controller. By adjusting the ratio by which the tapped pressures
are incorporated into the control pressure, an adjustment of the
ratio controller to different types of gas or burner valves or
excess-air factors is possible. The output pressure set by the
ratio controller can then be made constant over a wide power range.
To adjust a ratio controller, the ratio according to which the two
pressure taps are used to form a control pressure can be set either
by means of a three/two distribution valve, or by throttling only
one branch of the branching pulse channel, a fixed or adjustable
throttle valve being arranged in the other branch. The adjustment
can occur both manually and via a remote-controlled adjustment
device, for example, a magnetic valve, a servomotor, or the like.
The latter offers the possibility of subordinating gas quantity
regulation to a control device. The control device can be
connected, for example, to appropriate sensors that record the
calorific value of the gas, or the CO content, the O.sub.2 content
or the NOx content of the exhaust. Correction of the gas-air ratio
can then be effected on the basis of these measured values, in
which the correction again applies for a broad power range.
[0014] Additional advantages of the invention can be ascertained
from the drawings, the description, and/or the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] For a fuller understanding of the invention, reference is
had to the following description taken in connection with the
accompanying drawings, in which:
[0016] FIG. 1 shows a forced-air burner with ratio controller
connected in front, as well as additional gas valves to control
operation;
[0017] FIG. 2 shows the ratio controller according to FIG. 1 in a
schematic cross section;
[0018] FIG. 3 shows a modified embodiment of a ratio controller in
a schematic cross section;
[0019] FIG. 4 shows another modified embodiment of a ratio
controller in a schematic cross section;
[0020] FIG. 5 shows a ratio controller with remote-controlled
adjustment of the gas-air ratio in a schematic cross section;
[0021] FIG. 6 shows another modified embodiment of a ratio
controller in a schematic cross section; and
[0022] FIG. 7 shows a simplified embodiment of a ratio controller
in a schematic cross section.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] A forced-air burner 1 with a blower 2 connected upstream is
shown in schematic form in FIG. 1, the blower drawing in a gas-air
mixture. For this purpose, the blower 2 has an air jet 3 on the
input side, in which a gas nozzle 4 is arranged. This is fed from a
gas line 5, upstream of which a ratio controller 6 and control
valves 7 and 8 are connected. The latter serve to release and block
the gas. With control valves 7, 8 open, the ratio controller 6
serves to adjust a stipulated gas-air ratio independently of the
supply power of the blower 2, i.e., its speed. The ratio controller
6 performs this merely by tapping its own valve housing or the gas
line 5, without measurement or tapping of the amount of air. For
this purpose, on the path between the ratio controller 6 and gas
nozzle 4 at least two different flow cross sections are formed in
the gas line 5 or in the housing of ratio controller 6, from which
branches 9, 11 of a pulse line 12 branch off. This serves to
control a control drive 14 that regulates the ratio controller 6.
FIG. 2 can be referred to for an understanding of the layout and
function of the ratio controller 6. The ratio controller 6 shown
here has a housing 15, in which a through channel is formed. This
includes an inflow chamber 16 and an outflow chamber 17. A valve
seat 18 is formed between the two, which is associated with a valve
closure element 19. The latter is connected via a valve stem 21 to
the diaphragm 22 of an actuating diaphragm 23. The diaphragm 22
separates two working chambers 24, 25 in its housing. A spring 26
tightens the valve closure element 19 via the valve stem 21 against
valve seat 18. A connection channel 27 is arranged between the
outflow chamber 17 and the working chamber 24, whose underpressure
causes opening of the valve closure element 19, thus ensuring
pressure equalization between the outflow chamber 17 and the
working chamber 24.
[0024] In addition, two pressure taps in the form of openings 31,
32 are provided in the outflow chamber 17 or in the gas line 5
connected to its output 28, at which different flow conditions
prevail. For this purpose, for example, the outflow chamber 17 is
provided in a first region with a relatively large flow cross
section and in a second region with a relatively small flow cross
section. The measurement sites (openings 31, 32) are arranged in
these different regions. Gas flows of different velocity
accordingly prevail in front of these openings 31 32, so that
different pressures are recorded at the openings 31, 32. Branches
9, 11 extend away from the measurement sites or openings 31, 32,
which belong to the pulse line 12. The branches 9, 11, for example,
lead to a throttle valve block 33, which combines the two branches
9, 11 and connects them to a pressure measurement line 34, also
belonging to the pulse line 12. The throttle valve block 33
combines the two branches 9, 11, for example, as a T- or Y-branch.
A fixed throttle valve 35 can be arranged in branch 9. An
adjustable throttle valve 36 is preferably arranged in branch 11.
This can be formed by a reversing screw 37 that is screwed into the
throttle valve block 33 and is sealed to the outside, and whose
pointed end opens branch 11 more or less, depending on the
adjustment. If necessary, the function can also be reversed, with
the throttle valve 35 being adjustable and the throttle valve 36
being fixed. If necessary, both throttle valve valves can be made
adjustable.
[0025] The pressure measurement line 34 leads to a pilot valve 38.
This has a diaphragm 41, accommodated in a housing 39, that is
arranged in the immediate vicinity of a gas outlet opening 42. The
diaphragm 41 separates housing 39 into an air chamber 43 and a
control chamber 44. The control chamber 44 is connected to the
pressure measurement line 34. The pressure difference prevailing
between the air chamber 43 and the control chamber 44 determines
the position of diaphragm 41. This is arranged with reference to
the gas outlet opening 42, so that the gas outlet opening 42 is
closed when the air pressure predominates, whereas it has the
tendency to open when the gas pressure predominates. A spring 45,
which can be adjusted by means of an appropriate set screw 46,
adjusts the null point of the diaphragm 41, i.e., the pressure
ratio at which the diaphragm 41 lies precisely on opening 42. This
is a null point adjustment, wherein a change in mixing ratio,
dependent on power, can be achieved by changing the spring bias.
The lower power range is primarily influenced, however,
[0026] The gas outlet opening 42 is part of a line 47, with which
the gas pressure from the inflow chamber 16 is optionally tapped
via a throttle valve 48. A line 49 that leads to the working
chamber 25 branches off from line 47.
[0027] In the simplest case, the air chamber 43 is connected to the
surrounding air. Optionally, however, i.e., if desired, a
connection 51 can be provided with which the air chamber 43 can be
connected to a pressure measurement site that records the air
pressure in front of the mixture formation device. This is
particularly expedient if the pressure differs significantly from
the ambient air pressure.
[0028] In conjunction with the system shown in FIG. 1, the ratio
controller 6 described so far operates as follows:
[0029] With opening the control valves 7, 8 shown in FIG. 1 an
underpressure is produced by the blower 2 at air jet 3. This
initially passes through the gas line 6 and is therefore recorded
at measurement sites 31, 32. The underpressure reaches the pilot
valve 38, in the ratio established by the throttle valve block 33,
via the pressure measurement line 34 and therefore also generates a
certain underpressure in the control chamber 44. This leads to
closure of the gas outlet opening 42, so that the gas pressure
applied via line 47 is less reduced and can therefore reach the
working chamber 25 via line 49. At the same time, the underpressure
penetrating the outflow chamber 17 via the gas line acts on the
opposite side of diaphragm 22 via connection channel 27. A pressure
difference is therefore produced that moves the diaphragm 22 upward
and therefore moves the valve closure element 19 in the opening
direction. This process lasts until the prescribed reference
pressure at the gas nozzle 4 is reestablished in the outflow
chamber 17.
[0030] During this process, the gas velocity is taken into account,
and all the more so the further the reversing screw 37 is opened.
The gas flow produced by a specific underpressure at the gas nozzle
can therefore be finely regulated at the reversing screw 37. The
gas-air ratio is kept constant over a broad power range of the
forced-air burner 1, corresponding to a desired value. If the
blower speed and therefore the air supply increase, the
counterpressure on gas nozzle 4 drops simultaneously, which results
in a correspondingly increased gas flow. The extent to which the
gas flow increases with the increasing pressure drop can be set at
the reversing screw 37. Tapping a combustion chamber and other air
taps at the blower or burner are not necessary for this
purpose.
[0031] FIG. 3 shows a modified embodiment of the ratio controller
6. If agreement with the described embodiment exists, the same
reference numbers refer to the aforementioned description. The
difference between a ratio controller 6 according to FIG. 2 and
that according to FIG. 3 lies in the throttle valve block 33. This
is designed according to FIG. 3 as a three/two distribution valve.
The branches 9, 11 discharge in a common channel 52, in which a
spindle-like control element 53 is situated. This is connected to
the reversing screw 37. The pressure measurement line 34 branches
off in the vicinity of the mid-line of the regulation element 53.
With the regulation element 53, the ratio of the pressures tapped
from the measurement sites 31, 32 can be adjusted, which
contributes to formation of a control pressure for pilot valves
38.
[0032] The two embodiments just described start from fixed
measurement sites 31, 32. However, it is possible to get by with
only a single measurement site, if this is designed to be variable
in location. This is shown in FIG. 4 with reference to an
embodiment with a measurement site 55 provided at a rotary slide
valve 54. The rotary slide valve 54 forms a narrow passage in the
outflow chamber 17. Depending on the rotational position of the
rotary slide valve 54, the measurement site 55 is at a narrow
passage or (if rotated leftward in FIG. 4) at a wide location. The
rotary slide valve 54 is connected to the pulse line 12. With
rotation of the rotary slide valve 54, not only does the position
of the measurement site 55 change with reference to the flow rate
recorded, but so does its alignment relative to the flow direction.
The magnitude of the tapped pressure and the effect of the gas
velocity on it can therefore be regulated. As a result, the gas-air
ratio can be regulated for a broad load range by means of the
rotational position of rotary slide valve 54. Throttle valve block
33 can be dispensed with here. The pulse line is then connected
directly to pilot valve 38. Otherwise, the function of the ratio
controller 6 of this embodiment matches the function of the ratio
controller described above.
[0033] Another modified embodiment of the ratio controller 6 is
shown in FIG. 6. This is based largely on the embodiment according
to FIG. 4, and the description uses the same reference numbers.
However, instead of rotary slide valve 54 with only a single
measurement site 55, a combined gate valve 57 is provided that has
opening 32 at its front or, as shown, in its back. The gate valve
can be made cylindrical or cuboid. Branch 11 is connected to
opening 32, which is combined in the gate valve element with an
additional branch 9. Branch 9 is connected to opening 31. The gate
valve 57 can be pushed axially in order to more or less narrow the
channel leading from the outflow chamber 17. The pressure value
recorded at the opening 32 then changes accordingly. In addition,
adjustment of the gate valve for throttling branch 9 can be used.
However, it is preferable to make the cross section of the channels
making up branch 9 large enough so that full passage through
opening 31 into branch 9 and into pressure measurement line 34 is
present in each useful position of gate valve 57.
[0034] FIG. 7 shows another embodiment of the ratio controller 6,
based on the embodiment according to FIG. 4. The same reference
numbers apply to this description. However, instead of rotary slide
valve 54, which is penetrated transversely by a measurement
channel, a passive gate valve 58 is provided that is arranged
opposite measurement site 55. Depending on the gate valve position,
the free flow cross section prevailing in front of measurement site
55 is more or less narrowed. The gate valve can be a flat body
valve or a round body valve. It can be provided with a threaded
adjustment device or another means of adjustment. If it narrows the
flow channel before the measurement site 55, a larger flow rate
prevails here and a lower static gas pressure is tapped. If the
flow cross section is widened, a comparatively higher gas pressure
is tapped. This embodiment can also be used in an embodiment
related to the ratio controller 6 according to FIG. 6, in which the
line 12 is divided into two branches 9, 11, branch 9 leading to a
measurement site 31, as shown according to FIG. 6, whereas branch
11 leads to measurement site 55. In this arrangement, a fuel
gas/air ratio adjustment can also be effected by adjusting gate
valve 58.
[0035] All of the described ratio controllers 6 can be adjusted
manually. It is also possible to adjust the mentioned ratio
controller with a remote-controlled adjustment device, for example,
a servomotor 56, with respect to gas flow and therefore gas-air
ratio. FIG. 5 shows this based on the ratio controller according to
FIG. 2. Appropriate servomotors can, however, also be mounted on
the ratio adjustment devices of the other disclosed ratio
controllers 6. The servomotor 56 can be connected to a control
device that is not further shown in FIG. 1, and used to adjust the
gas-air ratio. This can be connected, for example, to appropriate
probes or sensors or input devices in order to produce an
adjustment signal from the measured operating conditions or control
commands.
[0036] To adjust a desired gas-air ratio on a burner over the
widest possible load range without additional pressure tapping from
the burner, a combustion chamber, or air lines, a ratio controller
6 is provided that permits an adjustment of the gas flow as a
function of counterpressure. For adjustment, the ratio controller 6
has at least one position-variable measurement site 55, or at least
two measurement sites 31, 32, that are connected via a valve block
or throttle valve block 33, directly or indirectly via a pilot
valve, to an actuating diaphragm 23. Depending on whether the
control pressure is picked up more from one or the other
measurement site, the gas flow and therefore the gas-air ratio can
be made smaller or larger.
[0037] While the description above refers to particular embodiments
of the present invention, it will be understood that many
modifications may be made without departing from the spirit
thereof. The accompanying claims are intended to cover such
modifications as would fall within the true scope and spirit of the
present invention.
[0038] The presently disclosed embodiments are therefore to be
considered in all respects as illustrative and not restrictive, the
scope of the invention being indicated by the appended claims,
rather than the foregoing description, and all changes which come
within the meaning and range of equivalency of the claims are
therefore intended to be embraced therein.
* * * * *